Collision Detection In Sprite Kit using Swift - swift

Question

The code below is from a project I am currently working on, I have been trying to teach myself Swift language and Sprite Kit for the past few days and this is my first attempt at a game, it is a Flappy Bird type game. I ran into a problem today when I was trying to write the code for the collision detection. When the bird touches one of the pipes the game is supposed to pause. However when I run the code and the bird touches the pipe, nothing happens, the bird just bounces off of it. I have read many tutorials and watched many videos on this subject to try and resolve my problem and haven't had any luck. I have written all of the collision detection code that I learned off of the last video I watched in the code below. Could anyone please tell me what I am doing wrong. Any advice would be greatly appreciated, thank you.
//
// GameScene.swift
// Bird Flappy Game
//
// Created by Brandon Ballard on 1/4/15.
// Copyright (c) 2015 Brandon Ballard. All rights reserved.
//
import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate {
var bird = SKSpriteNode()
var pipeUpTexture = SKTexture()
var pipeDownTexture = SKTexture()
var pipesMoveAndRemove = SKAction()
let pipeGap = 150.0
enum ColliderType:UInt32 {
case BIRD = 1
case PIPE = 2
}
override func didMoveToView(view: SKView) {
/* Setup your scene here */
backgroundColor = SKColor.cyanColor()
//physics
self.physicsWorld.gravity = CGVectorMake(0.0, -15.0);
self.physicsWorld.contactDelegate = self
func didBeginContact(contact: SKPhysicsContactDelegate) {
scene?.view?.paused = true
bird.setScale(12.0)
}
//Bird
var birdTexture = SKTexture(imageNamed:"Bird")
birdTexture.filteringMode = SKTextureFilteringMode.Nearest
bird = SKSpriteNode(texture: birdTexture)
bird.setScale(0.6)
bird.position = CGPoint(x: 375, y: self.frame.size.height * 0.6)
bird.physicsBody = SKPhysicsBody(circleOfRadius: bird.size.height / 2.0)
bird.physicsBody?.dynamic = true
bird.physicsBody?.allowsRotation = true
bird.physicsBody?.affectedByGravity = true
bird.physicsBody!.categoryBitMask = ColliderType.BIRD.rawValue
bird.physicsBody!.contactTestBitMask = ColliderType.PIPE.rawValue
bird.physicsBody!.collisionBitMask = ColliderType.PIPE.rawValue
self.addChild(bird)
//Ground
var groundTexture = SKTexture(imageNamed: "Ground")
var sprite = SKSpriteNode(texture: groundTexture)
sprite.setScale(2.0)
sprite.position = CGPointMake(self.size.width / 2, sprite.size.height / 2.0)
self.addChild(sprite)
var ground = SKNode()
ground.position = CGPointMake(0, groundTexture.size().height + 0)
ground.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(self.frame.size.width, groundTexture.size().height * 2.0))
ground.physicsBody?.dynamic = false
self.addChild(ground)
//Pipes
//Create the Pipes
pipeUpTexture = SKTexture(imageNamed: "PipeUp")
pipeDownTexture = SKTexture(imageNamed: "PipeDown")
//Movement of Pipes
let distanceToMove = CGFloat(self.frame.size.width + 2.0 * pipeUpTexture.size().width)
let movePipes = SKAction.moveByX(-distanceToMove, y: 0.0, duration: NSTimeInterval(0.01 * distanceToMove))
let removePipes = SKAction.removeFromParent()
pipesMoveAndRemove = SKAction.sequence([movePipes,removePipes])
//Spawn Pipes
let spawn = SKAction.runBlock({() in self.spawnPipes()})
let delay = SKAction.waitForDuration(NSTimeInterval(2.0))
let spawnThenDelay = SKAction.sequence([spawn,delay])
let spawnThenDelayForever = SKAction.repeatActionForever(spawnThenDelay)
self.runAction(spawnThenDelayForever)
}
func spawnPipes() {
let pipePair = SKNode()
pipePair.position = CGPointMake(self.frame.size.width + pipeUpTexture.size().width * 2, 0)
pipePair.zPosition = -10
let height = UInt32(self.frame.size.height / 4)
let y = arc4random() % height + height
var pipeDown = SKSpriteNode(texture: pipeDownTexture)
pipeDown.setScale(2.0)////////
pipeDown.position = CGPointMake(3.0, CGFloat(y) + pipeDown.size.height + CGFloat(pipeGap) )
pipeDown.physicsBody = SKPhysicsBody(rectangleOfSize: pipeDown.size)
pipeDown.physicsBody?.dynamic = false
pipeDown.physicsBody!.affectedByGravity = false
pipeDown.physicsBody!.categoryBitMask = ColliderType.PIPE.rawValue
pipeDown.physicsBody!.contactTestBitMask = ColliderType.BIRD.rawValue
pipeDown.physicsBody!.collisionBitMask = ColliderType.BIRD.rawValue
pipePair.addChild(pipeDown)
var pipeUp = SKSpriteNode(texture: pipeUpTexture)
pipeUp.setScale(2.0)
pipeUp.position = CGPointMake(0.0, CGFloat(y))
pipeUp.physicsBody = SKPhysicsBody(rectangleOfSize: pipeUp.size )
pipeUp.physicsBody?.dynamic = false
pipeUp.physicsBody!.affectedByGravity = false
pipeUp.physicsBody!.categoryBitMask = ColliderType.PIPE.rawValue
pipeUp.physicsBody!.contactTestBitMask = ColliderType.BIRD.rawValue
pipeUp.physicsBody!.collisionBitMask = ColliderType.BIRD.rawValue
pipePair.addChild(pipeUp)
pipePair.runAction(pipesMoveAndRemove)
self.addChild(pipePair)
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
/* Called when a touch begins */
for touch: AnyObject in touches {
let location = touch.locationInNode(self)
bird.physicsBody?.velocity = CGVectorMake( 0, 0 )
bird.physicsBody?.applyImpulse(CGVectorMake(0,25))
}
}
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
}
}

Answer 1

From what I can see, you only need to DETECT collisions, not actually simulate them. For this, you need to set only the contactTestBitMask of the physicsBodies. You can set the collisionBitMask as 0.
bird.physicsBody!.collisionBitMask = 0
pipe.physicsBody!.collisionBitMask = 0
Also, as hamobi has already said, the didBeginContact method needs to be outside the didMoveToView method with the override keyword. (This question has the exact same problem as yours)
class GameScene: SKScene, SKPhysicsContactDelegate {
// ...
override func didMoveToView(view: SKView) {
self.physicsWorld.gravity = CGVector(dx: 0, dy: 0)
// set as delegate:
self.physicsWorld.contactDelegate = self
// ..
}
// should be called now
func didBeginContact(contact: SKPhysicsContact){
scene?.view?.paused = true
bird.setScale(12.0)
}
}

Answer 2

You put your didBeginContact INSIDE of didMoveToView. It's not callable from there. Put it in the body of your class